• Korean journal of food and cookery science
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• v.21 no.1 s.85
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• pp.84-93
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• 2005

The antibacterial activities of methanol extract and systematic solvent fractions( -hexane, chloroform, ethyl acetate, and butanol) from Korean common type figs at different ripening stages were tested by the broth dilution method against 8 representative food-poisoning bacteria- : L. monocytogenes, S. aureus, S. enteritidis, E. coli O157:H7, E. coli, Y. enterocolitica, V. parahaemolyticus, and S. typhimurium. The methanol extracts of unripened I and II showed stronger activity than that of the ripened figs especially against L. monocytogenes, S. enteritidis, E. coli O157:H7, Y. parahaemolyticus and S. typhimurium in 10 mg/mL. The systematic solvent fractions showed stronger antibacterial activities than the methanol extract, even al the lower concentrations. The hexane fraction of ripened figs showed higher growth inhibition than those of unripened I and II against L. monocytogenes, E. coli O157:H7, Y. enterocolitica and V. parahaemolyticus. The chloroform fraction showed strong antibacterial activity in all ripening stages against E. coli O157:H7 and V. parahaemolyticus. The butanol fraction showed better inhibition activity in unripened I and II than in the ripened figs. The hexane and chloroform fractions showed inhibition activity of more than $75\%$ against E. coli O157:H7, V. parahaemolyticus in 0.5 mg/mL. Each fraction showed a little different antibacterial activity according to the ripening stages of the fruits and the tested strains. Especially, figs in the unripened II stage revealed superior activity relatively and the hexane and chloroform fractions revealed the strongest activity, followed by the butanol fraction, while the ethylacetate and water fractions hardly showed any activity.

• Journal of the Korean Geotechnical Society
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• v.17 no.4
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• pp.331-339
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• 2001

인산석고(phosphogypsum)는 비료생산과정에서 발생되는 산업부산물로, 주요구성성분은 이수석고(CaSO$_4$.2$H_2O$)의 성분이 대부분이고 여기에 인(P$_2$O$_2$), 철(F)와 유기물질 등으로 이루어져 있다. 전 세계적으로 인산석고 발생량은 현재 1억8천만톤이고 향후 약 3억8천만톤 발생될 것으로 추정되며, 국내에는 약 157만톤이 발생되고 있다. 본 연구는 성토재료로 인산석고를 활용할 경우 이에 대한 물리적 환경적 특성을 분석하였다. 이를 위하여 인산석고와 화강토 혼합비율에 따른 입도분석, 비중시험, 다짐시험, CBR시험, pH시험 및 용출시험 등 일련의 실험을 실시하였다. 실험결과, 인산석고 혼합재료를 성토재료로 활용할 경우 환경적으로 유해한 영향이 적으며, 산업부산물의 자원화 차원에서 대체 성토재료로 활용이 가능한 것으로 나타났다.

• Korean Journal of Veterinary Research
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• v.30 no.3
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• pp.287-295
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• 1990

The purpose of this study was the examination for presence of pilus antigen, O serogroups, colicin production, antibiotic susceptibility and plasmid profiles among E coli isolated from diarrheal piglets and fattening pigs in Taegu province. Of 145 E coli isolated, 98 strains (67.4%) possesed pilus antigens which belonged to either K88 (47.6%), K99 (11.7%) or 987P (8.3%) types. Fifty-nine strains (40.7%) were classified into tenO serogroups and their types were O8 (22.0%), O20(16.9%), O141(15.3%), O9(10.2%), O45(10.2%), O139(8.5%), O064(6.8%), O149(5.0%), O157(3.4%), and O115(1.7%). Thirty-three strains (22.8%) were colicinogenic and 6 strains (4.1%) were hemolytic. One hundred and thirty-nine strains (95.9%) of 145 E coli isolates were resistant to ampicillin, chloramphenicol, gentamicin, kanamycin, streptomycin, tetracycline, rifampicin and nalidixic acid, alone or in combination thereof. Ninety strains (64.7%) of 139 drug resistant strains carried R factor (R) which were transferable to the recipient by conjugation. In gel electrophoresis for the isolation of plasmid DNA, the number of plasmid DNA band varied from 2 to 11 in 16 E coli with pilus antigen. It's molecular weight ranged from 1.0 to 60.0 megadalton.

• Journal of Industrial Technology
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• v.25 no.A
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• pp.157-162
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• 2005

In this study, the fabrication of PZT films was performed from a multilayer structure comprising $TiO_2$, $ZrO_2$ and PbO thin films prepared by rapid themal chemical vapor deposition(RTMOCVD). $TiO_2$, $ZrO_2$ and PbO are the component layers of oxide multilayer system for a single phase PZT thin film. The composition control of PZT thin film was done by the thickness control of individual component layer. The composition ratio of Pb:Ti:Zr with thickness were 1:0.94:0.55. Occurrence of a single-phase of PZT was initiated at around $550^{\circ}C$ and almost completed at $750^{\circ}C$ under the fixed time of 1hr. As the concentration of Pb increased, the roughness and crystallization in the film increased. From the as result of using XPS and TEM, the single phase formation through annealing is evident. The electrical properites of the prepared PZT thin film(Zr/Ti=40/60, 300 nm) on a Pt-coated substrate were as follow: dielectric constant ${\varepsilon}_r=475$, coercive field Ec=320 kV/cm, and remanant polarization $P_r=11{\mu}C/cm^2$ at an applied voltage of 18 V.

• Microbiology and Biotechnology Letters
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• v.44 no.1
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• pp.98-105
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• 2016

The presence of bacterial strains showing antagonistic activity to common pathogens found in a variety of fermented foods in Korea was explored. A bacterium inhibiting the growth of pathogens such as Aspergillus terreus (KCTC6178), A. flavus (KCTC6984), Staphylococcus aureus (KCCM12214), Escherichia coli O157:H7 (KCCM40406), Bacillus cereus (KCTC1012), Cryptococcus neoformans (ATCC208821), Salmonella typhimurium (ATCC19430), and Listeria monocytogenes (KCTC3569) was isolated from Makgeolli, a Korean traditional rice wine. The strain showing high antipathogenic activity was identified as B. amyloliquefaciens based on the nucleotide sequence of the 16S ribosomal RNA gene. Compared with B. amyloliquefaciens KCTC1660, whose genome has been sequenced, the isolate exhibited significantly low activities of starch-degrading enzymes and high resistance to high temperature and low pH.

• Korean journal of food and cookery science
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• v.31 no.2
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• pp.153-161
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• 2015

This study was conducted to investigate the consumption practices of ready-to-eat (RTE) foods and to analyze the microbiological hazard of kimbab, a Korean dish, and the most popular of the RTE foods eaten by participants in this study. A questionnaire was distributed to 230 university students who had previously purchased RTE foods, and 224 were collected (response rate: 97.4%). Statistical analyses were conducted on the questionnaires using the SPSS program, and a total of 135 kimbab products were sampled for aerobic plate counts, coliforms, E. coli, E. coli O157:H7, Staphylococcus aureus, Salmonella spp., and Listeria monocytogenes. The results of the analyses are as follows. Kimbab (87.0%), sandwich (86.4%), hamburger (89.8%), lunchbox (81.5%), and sushi (87.4%) were most often eaten immediately after purchasing. Additionally, the results of the microbiological hazards analysis of kimbab showed that the aerobic plate counts were significantly different according to the purchasing price (p<0.01). The coliform levels were significantly different according to the place of purchase (p<0.01) and the major ingredients of kimbab (p<0.05). In addition, Staphylococcus aureus and E. coli were detected in 5.9% and 5.2% of the tested samples, respectively. However, E. coli O157:H7, Salmonella spp., and Listeria monocytogenes were not detected in any of the samples. In conclusion, the manufacturers of RTE foods should apply the HACCP system for food safety.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.157-157
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• 2010

Vertical-structure light-emitting diodes (V-LEDs) by laser lift-off (LLO) have been exploited for high-efficiency GaN-based LEDs of solid-state lightings. In V-LEDs, emitted light from active regions is reflected-up from reflective ohmic contacts on p-GaN. Therefore, silver (Ag) is very suitable for reflective contacts due to its high reflectance (>95%) and surface plasmon coupling to visible light emissions. In addition, low contact resistivity has been obtained from Ag-based ohmic contacts annealed in oxygen ambient. However, annealing in oxygen ambient causes Ag to be oxidized and/or agglomerated, leading to degradation in both electrical and optical properties. Therefore, preventing Ag from oxidation and/or agglomeration is a key aspect for high-performance V-LEDs. In this work, we demonstrate the enhanced thermal stability of Ag-based Ohmic contact to p-GaN by reducing the thermal compressive stress. The thermal compressive stress due to the large difference in CTE between GaN ($5.6{\times}10^{-6}/^{\circ}C$) and Ag ($18.9{\times}10^{-6}/^{\circ}C$) accelerate the diffusion of Ag atoms, leading to Ag agglomeration. Therefore, by increasing the additional residual tensile stress in Ag film, the thermal compressive stress could be reduced, resulting in the enhancement of Ag agglomeration resistance. We employ the thin Ni layer in Ag film to form Ni/Ag mutli-layer structure, because the lattice constant of NiO ($4.176\;{\AA}$ is larger than that of Ag ($4.086\;{\AA}$). High-resolution symmetric and asymmetric X-ray diffraction was used to measure the in-plane strain of Ag films. Due to the expansion of lattice constant by oxidation of Ni into NiO layer, Ag layer in Ni/Ag multi-layer structure was tensilely strained after annealing. Based on experimental results, it could be concluded that the reduction of thermal compressive stress by additional tensile stress in Ag film plays a critical role to enhance the thermal stability of Ag-based Ohmic contact to p-GaN.

• Korean journal of food and cookery science
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• v.28 no.1
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• pp.9-15
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• 2012

This study analyzed the antibacterial activity of a Rubus coreanum (Bokbunja) ethanol extract. The antimicrobial activity was determined by disc diffusion, minimum inhibitory concentration (MIC), and growth inhibition methods with seven kinds of bacteria related to foodborne illness (Bacillus cereus, Escherichia coli, Escherichia coli O157:H7, Listeria monocytogenes, Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella typhimurium). In the results, disc diffusions of the ethanol extract from R. coreanum (9.8-17.5 mm at $4,000{\mu}g/disc$) clearly showed the antimicrobial activity of the extract against all tested microorganisms. Rubus coreanum promoted an inhibitory effect as follows: E. coli O157:H7 > P. aeruginosa > L. monocytogenes > E. coli > S. aureus > B. cereus ${\geq}$ S. typhimurium. In the MIC test, R. coreanum showed high antimicrobial effect against L. monocytogenes at 500 ppm. Moreover, the R. coreanum ethanol extract showed strong growth inhibition against microorganisms, similar to the MIC results. These results show that a R. coreanum ethanol extract has powerful antimicrobial activity against all tested microorganisms, suggesting that R. coreanum will be useful as a potential natural preservative.

• Journal of Environmental Health Sciences
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• v.33 no.2 s.95
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• pp.150-157
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• 2007

The chemical and photochemical decolorization of Rhodamine B (RhB) in water has been carried out by Fenton, Fenton-like and photo-Fenton-like process. The effect of applied $H_2O_2,\;Fe^{2+}$ dosage (Fenton process), $H_2O_2,\;Fe^{\circ}$ dosage (Fenton-like and photo-Fenton-like process), UV light power (photo-Fenton-like process) pH (all processes) have been studied. The results obtained showed that more than 98% of color removal was obtained for the RhB solutions in every process. However, Fenton-like process was not suitable for the color removal of RhB because Fenton-like process was required much more reagents than Fenton and photo-Fenton-like process. The Fenton and photo-Fenton-like process showed similar reagents need. Optimum pH for three processes in this study is about pH 3. The relative order of sensitivity for pH of each process was: Fenton-like > photo-Fenton-like > Fenton.

• Korean Journal of Food Science and Technology
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• v.48 no.5
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• pp.486-491
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• 2016

Efficacy of dielectric barrier discharge-cold plasma treatment (DBD-CPT) for microbial decontamination of onion powder was evaluated. Onion powder, inoculated with Escherichia coli O157:H7, Salmonella Enteritidis, or Listeria monocytogenes, was treated with helium DBD-CPT. DBD-CPT (9 kV, 20 min) inhibited E. coli O157:H7, S. Enteritidis, and L. monocytogenes by $1.4{\pm}0.5$, $2.3{\pm}0.3$, and $1.2{\pm}0.0log\;CFU/cm^2$, respectively. The inactivation levels of E. coli O157:H7, S. Enteritidis and L. monocytogenes increased by $2.2{\pm}0.1$, $2.5{\pm}0.1$ and $1.9{\pm}0.3log\;CFU/cm^2$, respectively, as water activity increased from 0.4 to 0.8, and increased by $2.3{\pm}0.4$, $2.1{\pm}0.1$ and $1.6{\pm}0.1log\;CFU/cm^2$, respectively, as the particle size increased from 0.3 to $1.0cm^2$. Neither the ascorbic acid and quercetin concentrations nor the color of onion powder was changed by DBD-CPT (p>0.05). These results demonstrate the potential for application of DBD-CPT in improving microbiological safety of onion powder while preserving the physicochemical properties.